Condensing a defect scan log for a disk of a disk drive

ABSTRACT

The embodiments relate to optimizing a defect log of a storage device, such as a disk drive. The defect log may comprise entries for individual locations, such as sectors on a disk, and entries indicating zones. A zone comprises a plurality of locations in the medium of the storage device and may contain adjacent or non-adjacent defects. One or more medium of the storage device may be scanned for defects and locations of these defects are recorded in the defect log. The defect log may then be analyzed to determine if certain number of defects are in proximity to each other, adjacent or non-adjacent, within a zone. If the defects within a zone exceed a threshold, then the defect log may be condensed by coalescing the individual entries of the defects into zone entries. In addition, the defect log may be further condensed by coalescing zone entries of adjacent zones into combined entries.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/399,762, now U.S. Pat. No. 8,040,625, entitled “CONDENSING A DEFECTSCAN LOG FOR A DISK OF A DISK DRIVE,” which was filed on Mar. 6, 2009,and is incorporated by reference in its entirety.

BACKGROUND

A huge market exists for disk drives for mass-market computing devicessuch as desktop computers and laptop computers, as well as small formfactor (SFF) disk drives for use in mobile computing devices (e.g.personal digital assistants (PDAs), cell-phones, digital cameras, etc.).To be competitive, a disk drive should be relatively inexpensive andprovide substantial capacity, rapid access to data, and reliableperformance.

Disk drives typically employ a moveable head actuator to frequentlyaccess large amounts of data stored on a disk. One example of a diskdrive is a hard disk drive. A conventional hard disk drive has a headdisk assembly (“HDA”) including at least one magnetic disk (“disk”), aspindle motor for rapidly rotating the disk, and a head stack assembly(“HSA”) that includes a head gimbal assembly (HGA) with a moveabletransducer head for reading and writing data. The HSA forms part of aservo control system that positions the moveable transducer head over aparticular track on the disk to read or write information from and tothat track, respectively.

Typically, a conventional hard disk drive includes one or more diskswherein each disk includes a plurality of concentric tracks. Eachsurface of each disk conventionally contains a plurality of concentricdata tracks angularly divided into a plurality of data sectors. Inaddition, special servo information may be provided on each disk todetermine the position of the moveable transducer head. The moveabletransducer head typically includes a writer and a reader.

The most popular form of servo is called “embedded servo” wherein theservo information is written in a plurality of servo wedges that areangularly spaced from one another and are interspersed between andwithin data sectors around each track of each disk. Each servo wedgetypically includes at least a phase locked loop (PLL) field, a servosync mark (SSM) field, a track identification (TKID) field, a sector IDfield having a sector ID number to identify the sector, and a group ofservo bursts (e.g. an alternating pattern of magnetic transitions) thatthe servo control system of the disk drive samples to align the moveabletransducer head with or relative to a particular track. Typically, theservo control system moves the transducer head toward a desired trackduring a “seek” mode using the TKID field as a control input. Once themoveable transducer head is generally over the desired track, the servocontrol system uses the servo bursts to keep the moveable transducerhead over that track in a “track follow” mode.

During disk drive manufacturing, the disk of the disk drive is scannedto detect defects that are present on the disk. A log is generated toindicate the locations of the defects detected on the disk. The logtypically has a finite size. If the log becomes full before the entiresurface of the disk is scanned, the disk drive fails the manufacturingprocess.

The presently-utilized disk drive manufacturing process that fails thedisk drive when the finite sized log becomes full unfortunately failsdisk drives that are actually capable of passing the manufacturingprocess. This is because, oftentimes, the continued scanning of theremaining surface of the disk may yield fewer defects such that the diskcan still be formatted to achieve the targeted storage capacity for thedisk of the disk drive.

Therefore, there is a need in the disk drive manufacturing process toenable further scanning of the disk and to not fail a disk drive basedsolely on an overflowing log.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified block diagram of a disk drive, in whichembodiments of the invention may be practiced.

FIG. 2 shows a disk of disk drive having a plurality of concentrictracks, and more particularly, illustrates a disk that includes servowedges, in accordance with one embodiment of the invention.

FIG. 3 is a flow diagram of a process to condense a defect scan log fora disk during disk drive manufacturing, according to one embodiment ofthe invention.

FIG. 4 is a diagram showing an example of a plurality of defect zonesdivided across physical locations of the disk and, particularlyillustrates, defects located within defect zones, according to oneembodiment of the invention.

FIG. 5A is a table showing a log before coalescing by the disk drive,according to one embodiment of the invention.

FIG. 5B illustrates a table showing the previously-described log of FIG.5A after coalescing, according to one embodiment of the invention.

FIG. 6 is a flow diagram of a process to determine if two or more defectzones are adjacent to one another, according to one embodiment of theinvention.

DETAILED DESCRIPTION

FIG. 1 shows a simplified block diagram of a disk drive 30, in whichembodiments of the invention may be practiced. Disk drive 30 comprises aHead/Disk Assembly (HDA) 34 and a controller printed circuit boardassembly (PCBA) 32. Host 36 may be a computing device such as a desktopcomputer, a laptop computer, a server computer, a mobile computingdevice (e.g. PDA, camera, cell-phone, etc.), or any type of computingdevice. Alternatively, host 36 may be a test computer that performscalibration and testing functions as part of the disk drivemanufacturing process. Disk drive 30 may be of a suitable form factorand capacity for computers or for smaller mobile devices (e.g. a smallform factor (SFF) disk drive).

HDA 34 comprises: one or more disks 46 for data storage; a spindle motor50 for rapidly spinning each disk 46 (four shown) on a spindle 48; andan actuator assembly 40 for moving a plurality of heads 64 over eachdisk 46. Actuator assembly 40 includes a plurality of actuator arms 41having heads 64 attached to distal ends thereof, respectively, such thatthe actuator arms 41 and heads 64 are rotated about a pivot point sothat the heads sweep radially across the disks 46, respectively. Theheads 64 are connected to a preamplifier 42 via a cable assembly 65 forreading and writing data on disks 46. Preamplifier 42 is connected tochannel circuitry in controller PCBA 32 via read data line 92 and writedata line 90.

Controller PCBA 32 may include a read/write channel 68, servo controller98, host interface and disk controller (HIDC) 74, voice coil motor (VCM)driver 102, spindle motor driver (SMD) 103, microprocessor 84, andseveral memory arrays—buffer or cache memory 82, RAM 108, andnon-volatile memory 106.

Host initiated operations for reading and writing data in disk drive 30may be executed under control of microprocessor 84 connected to thecontrollers and memory arrays via a bus 86. Program code executed bymicroprocessor 84 may be stored in non-volatile memory 106 and randomaccess memory RAM 108. Program overlay code stored on reserved tracks ofdisks 46 may also be loaded into RAM 108 as may be needed for execution.

During disk read and write operations, data transferred by preamplifier42 may be encoded and decoded by read/write channel 68. During readoperations, read/write channel 68 may decode data into digital bitstransferred on an NRZ bus 96 to HIDC 74. During write operations, HIDCmay provide digital data over the NRZ bus to read/write channel 68 whichencodes the data prior to its transmittal to preamplifier 42. As oneexample, read/write channel 68 may employ PRML (partial response maximumlikelihood) coding techniques, although other coding processes may alsobe utilized.

HIDC 74 may comprise a disk controller 80 for formatting and providingerror detection and correction of disk data, a host interface controller76 for responding to commands from host 36, and a buffer controller 78for storing data which is transferred between disks 46 and host 36.Collectively the controllers in HIDC 74 provide automated functionswhich assist microprocessor 84 in controlling disk operations.

Servo controller 98 provides an interface between microprocessor 84 andactuator assembly 40 and spindle motor 50. Microprocessor 84 commandslogic in servo controller 98 to position actuator assembly 40 using aVCM driver 102 and to precisely control the rotation of spindle motor 50with a spindle motor driver 103. For example, disk drive 30 may employ asampled servo system in which equally spaced servo wedges are recordedon each track of each disk 46. Data sectors are recorded in theintervals between servo wedges on each track. Data sectors may also besplit such that a single data sector is recorded on both sides of anintervening servo wedge. Servo wedges are sampled at regular intervalsby servo controller 98 to provide servo position information tomicroprocessor 84. Servo wedges are received by read/write channel 68,and are processed by servo controller 98 to provide position informationto microprocessor 84 via bus 86.

FIG. 2 shows a disk 46 of disk drive 30 of FIG. 1 having a plurality ofconcentric tracks, and more particularly, illustrates a disk 46 thatincludes servo wedges 14 in accordance with one embodiment of theinvention. The plurality of servo wedges 14 are servo-writtencircumferentially around disk 46 to define circumferential tracks 12 andare utilized in seeking and track following. In particular, embeddedservo wedges 14 a, 14 b, etc., contain servo information utilized inseeking and track following and are interspersed between data regions 15of the disk 46. Data is conventionally written in the data regions 15 ina plurality of discrete data sectors. Each data region 15 is typicallypreceded by a servo wedge 14.

Each servo wedge 14 may include: a phase lock loop (PLL) field 20, aservo sync mark (SSM) field 22, a track identification (TKID) field 24,a sector identifier (ID) field 26, and a group of servo bursts (e.g.ABCD) 28 (e.g. an alternating pattern of magnetic transitions) that theservo control system samples to align the moveable transducer head with,and relative to, a particular track. Typically, servo controller 98moves head 64 toward a desired track during a “seek” mode using the TKIDfield 24 as a control input. In order to perform seeking and trackfollowing operations by servo controller 98, a servo field sync-upoperation is performed to detect a servo wedge 14. A preamble—such asthe phase lock loop (PLL) field 20—is generally read first by theread/write channel 68 as part of a servo field sync-up operation torecover the timing and gain of the written servo wedge 14. For example,the PLL field may be written with a 2T pattern, as is well known in theart. Next, the servo sync mark (SSM) 22 is read to facilitate blocksynchronization. The SSM 22 facilitates block synchronization by actingas a special marker that is detected to “frame” data, i.e., to identifya boundary of a block. Servo field sync-up operations to detect a servopreamble, such as PLL 20, to recover the timing and gain of a writtenservo sector and to detect the servo sector for servo control operationsare well known in the art.

Once head 64 is generally over a desired track 12, servo controller 98uses the servo bursts (e.g. ABCD) 28 to keep head 64 over the track in a“track follow” mode. During track following mode, head 64 repeatedlyreads the sector ID 26 of each successive servo wedge to obtain thebinary encoded sector ID number that identifies each wedge of the track.Based on the TKID and sector ID, servo controller 98 continuously knowswhere head 64 is relative to disk 46 and communicates this tomicroprocessor 84. In this way, the microprocessor 84 continuously knowswhere the head 64 is relative to the disk and can command the movementof the head 64, via the servo control system, to implement disk driveoperations, suck as seeking, tracking, read/write operations, etc.

In one embodiment, microprocessor 84 may operate under the control of aprogram or routine to execute methods or processes in accordance withembodiments of the invention related to condensing a defect scan log fora disk 46. Microprocessor 84 may perform operations comprising:determining a plurality of defect zones on disk 46 in which each defectzone includes a plurality of physical locations on disk 46, detectingdefects on disk 46, and recording those defects into a defect scan logas log entries wherein the log entries comprise a location parameterrelated to the defect location on disk 46. Further, microprocessor 84may execute operations comprising determining that the number of defectsdetected in a first defect zone exceed a first threshold, and, if so,combining the log entries of the first defect zone into a coalesced logentry. For example, such a program may be implemented in software orfirmware (e.g., stored in non-volatile memory 106 or other locations)and may be implemented by microprocessor 84. Also, although this processis described with reference to one disk 46, it may often be performed onmultiple disks 46.

For the purposes of the present specification, it should be appreciatedthat the terms “processor”, “microprocessor”, and “controller”, etc.,refer to any machine or selection of logic that is capable of executinga sequence of instructions and should be taken to include, but notlimited to, general purpose microprocessors, special purposemicroprocessors, central processing units (CPUs), digital signalprocessors (DSPs), application specific integrated circuits (ASICs),signal processors, microcontrollers, etc. Further, it should beappreciated that the term processor, microprocessor, circuitry,controller, etc., refer to any type of logic or circuitry capable ofexecuting logic, commands, instructions, software, firmware,functionality, etc.

Thus, processor 84 controls operations in disk drive 30 to condense adefect scan log for a disk 46. In particular, processor 84 controls aprocess for condensing the defect scan log for the surface of disk 46during the manufacturing process to allow for the further scanning ofthe disk surface to potentially make the surface of the disk usable tomeet the targeted storage capacity for the disk drive 30.

FIG. 3 is a flow diagram of a process 300 to condense a defect scan logfor a disk during disk drive manufacturing, according to one embodimentof the invention. In one embodiment, process 300 may be implemented byprocessor 84 under the control of a program.

In process 300, a plurality of defect zones are determined (block 305).Each defect zone includes a plurality of physical locations on the disk.Next, defects on the disk are detected (block 310). At decision block312, process 300 determines if the defect detection process is complete,and if so, process 300 ends (block 314), and if not, process 300 recordsdefects into a defect scan log as log entries (block 315). In oneembodiment, each log entry may comprise a location parameter related tothe defect location on the disk, as will be described in more detail.

In one optional embodiment, process 300 determines whether the number oflog entries exceed a second threshold (decision block 317). If the logentries do exceed this second threshold, then process 300 moves on todecision block 320. If not, then process 300 returns to block 310 todetect defects on the disk. This second threshold may be utilized todetermine if the number of log entries at least meet a pre-determinedthreshold of detected defects before moving on with process 300 in whichcoalescing may occur.

At decision block 320, process 300 determines whether the number ofdefects in a defect zone exceed a first threshold. If the number ofdefects in the defect zone exceed a first threshold, then the logentries of the defect zone are combined into a coalesced log entry(block 325).

If the number of defects in a defect zone do not exceed a firstthreshold or if they have been combined into a coalesced log entry, thenprocess 300 moves on to decision block 322 where it is determinedwhether coalescing is finished such as when all of the defect zones havebeen processed. If coalescing is finished, process 300 moves on tocircle A, as will be described. If not, process 300 moves back todecision block 320.

FIG. 4 is a diagram showing an example of a plurality of defect zones402 divided across physical locations of the disk and, particularlyillustrates, defects located within the defect zones, according to oneembodiment of the invention. As shown in FIG. 4, a plurality ofequally-spaced defect zones 402 across a portion of the disk have beendetermined and illustrate defects 404 that are located within each ofthe defect zones. Although, equally-spaced defect zones are described,it should be appreciated that differently-sized defect zones may also beutilized.

In one embodiment, the defect zones may be equally-spaced and dividedacross a disk space, as shown in FIG. 4, along an x-axis denoting tracklocation 410 and a y-axis 412 denoting wedge locations. Thus, in thisexample, along the x-axis, tracks of the disk between 2800-3000 areshown and each defect zone 402 includes a range of 20 tracks. Whereasalong the y-axis wedges 0-220 are shown wherein each defect zone 402 isdivided into 20 wedges. Accordingly, for each equally-sized defect zone,each defect zone 402 is divided into a length of 20 tracks and 20wedges. It should be appreciated that this is just one example of howdefect zones may be sub-divided on a disk to illustrate physicallocations on the disk and a wide variety of differing sizes, lengths,etc., may be utilized.

As an example, a defect zone 430 is shown between tracks 2800-2820 andwedges 20-40. In this defect zone, there are two defects 432 and 434that have been detected. Similarly, another defect zone 440 has beendetermined between tracks 2800-2820 and wedges 60-80 that includes eightdetected defects (441, 442, 443, 444, 445, 446, 447, and 448).

Each of these defects that have been detected are recorded into a defectscan log as a log entry wherein each log entry includes a locationparameter related to the defect location on the disk.

FIG. 5A is a table showing a log before coalescing 500 by the diskdrive, according to one embodiment of the invention. Log 500 includes atrack measurement 502 and a wedge measurement 504 for each defect thathas been detected. There is also a track count column 503 and a wedgecount column 507 that indicate that each defect has a denoted trackcount and wedge count of 1.

As an example, with reference also to FIG. 4, defect 441 is identifiedat line 510. Defect 442 is identified at log line 512. Defect 432 isidentified at log line 514. Defect 443 is identified at log line 516.Defect 450 is identified at log line 518. Defect 444 is identified atlog line 520. Defect 445 is identified at log line 522. Defect 446 isidentified at log line 524. Defect 447 is identified at log line 526.Defect 434 is identified at log line 528. Defect 452 is identified atlog line 530. Lastly, defect 448 is identified at log line 532.

Thus, the log before coalescing 500 identifies each detected defect interms of track location and wedge location. Further, as can be seen bylog 500, examples of defect locations for detected defects for defectzones between 2820-2840 and wedges 0-220 are also listed. It should beappreciated that the log before coalescing 500 can be used to cover allof the identified defects as shown in the example of FIG. 4 coveringtracks 2800-3000 and wedges 0-220. The log before coalescing size can bepre-determined based upon testing criteria for the disk.

FIG. 5B is a table showing the previously-described log from FIG. 5Aafter coalescing 520, according to one embodiment of the invention. Toillustrate the results of coalescing, with reference also to defect zone440 of FIG. 4, all of the defects 441, 442, 443, 444, 445, 446, 447, and448 have been detected and those defects have been recorded into thedefect scan log 500 before coalescing, as previously described. Afterdetermining that the number of defects detected in defect zone 440exceeded a first threshold (e.g. greater than two defects) the logentries 510, 512, 516, 520, 522, 524, 526, and 532 are coalesced intoline 550 of the log after coalescing 520.

The log after coalescing table 520 includes a track start column, atrack count column, a wedge start column, a wedge count column, andoptionally a number of defects column. Thus, coalesced log entry line550 shows a track start of 2800, a track count of 20, a wedge start of60, a wedge count of 20, and 8 defects thereby illustrating a condensedlog entry with 8 defects. This corresponds to defect zone 440 of FIG. 4.Thus, the coalesced log entry includes defects detected on the disk thatare in proximity to one another along a first axis 412 corresponding toa circumferential direction for the plurality of wedges and a secondaxis 410 corresponding to a radial direction for the plurality oftracks.

It should be appreciated that different thresholds for the amount ofdefects required to be detected may be chosen based upon testingconsiderations (greater than two being only one example). If thethreshold is not met the log entry remains in the log after coalescing,such as shown by lines 552 and 554.

Thus, the processor of the disk drive controls operations in the diskdrive to condense a defect scan log for a scanned disk. In particular,the processor provides a process for condensing a defect scan log for asurface of a disk during the manufacturing process to allow for thefurther scanning of the disk such that the disk drive is not failed dueto an overflowing log. In particular, this process by utilizing acoalescing algorithm combines log entries that are in close proximityinto a single entry to free up log space for further entries. Thisprocess may occur multiple times in the defect scanning process.Accordingly, embodiments of the invention relate to a method ofcoalescing a defect scan log generated in a disk drive manufacturingprocess to enable further scanning and to avoid failing a disk drive dueto an overflowing log.

Further, two or more defect zones that are adjacent to one another mayalso be combined to further reduce the size of the defect scan log.

FIG. 6 is a flow diagram of a process 600 to determine if two or moredefect zones are adjacent to one another and, if so, to combine theadjacent coalesced log entries, according to one embodiment of theinvention. In particular, continuing from circle A from FIG. 3, afterthe number of defects detected in a second defect zone are determined toexceed the first pre-determined threshold and the log entries of thesecond defect zone are combined into a second coalesced log entry, atdecision block 610, process 600 then determines whether the first andsecond defect zones are adjacent to one another. If so, at block 635,the first and second coalesced log entries are combined into a thirdcoalesced log entry.

Next, at block 620, whether or not adjacent defect zones are present,process 600 determines whether the number of sectors identified in thelog after coalescing exceeds a threshold value (decision block 620). Ifso, then the disk has too many defects such that it is unusable and thedisk drive has failed the manufacturing process and the process ends(block 630). However, if the threshold value is not exceeded, then theprocess to detect defects on the disk continues at circle B (see FIG.3). The threshold value may be fixed or may change in some embodiments.For example, in embodiments with multiple disk surfaces, the thresholdvalue may be relaxed for one disk surface if one or more other disksurfaces had few defects, which resulted in higher available capacityfrom the other disk surfaces to meet a targeted capacity point for thedisk drive.

In one optional embodiment, process 600 may further determine whetherthe number of log entries exceed a second threshold prior to determiningthat number of defects detected in the first and second defect zonesexceed the first pre-determined threshold. If so, process 600 continuesto decision block 610. If not, process 600 continues to decision block620. This second threshold may be utilized to determine if the number oflog entries at least meet a pre-determined threshold of detected defectsbefore moving on with process 600 in which coalescing may occur.

To illustrate an example of the combining of adjacent defect zones, asshown in FIG. 4, a first defect zone 460 between tracks 2820-2840 andwedges 100-120 is detected and the individual defects are written intothe log before coalescing 500. A second defect zone 470 between tracks2820-2840 and wedges 120-140 is also detected and the individual defectsare written into the log before coalescing 500. Further, a firstcoalesced log entry is written in the log after coalescing 520 for thefirst defect zone and a second coalesced log entry is written in the logafter coalescing 520 for the second defect zone.

Next, after the first and second defect zones 460 and 470 are determinedto be adjacent to one another, the first and second coalesced logentries for these first and second defect zones are combined into athird coalesced log entry.

For example, at line 570 of the table for the log after coalescing 520,it can be seen that both the log entries for the adjacent defect zones460 and 470 have been coalesced into line 570 having a track start at2820 with a track count of 20, a wedge start at 100 with a wedge countof 40, and having a total number of 12 defects.

Embodiments of the invention provide a process and method for coalescinga defect scan log generated by a disk drive during the manufacturingprocess such that a disk drive is not improperly failed due to anoverflowing of the log. In particular, a process is provided forcondensing a defect scan log for a scanned disk during the manufacturingprocess to allow further scanning of the disk surface and potentiallymaking the surface of the disk usable to meet the targeted storagecapacity for the disk drive. In this way, the disk drive manufacturingprocess is improved.

While embodiments of the invention and its various functional componentshave been described in particular embodiments, it should be appreciatedthat the embodiments can be implemented in hardware, software, firmware,or combinations thereof.

The methods and processes previously described can be employed for diskdrives with embedded servo systems. However, numerous alternatives fordisk drives or other types of storage devices with similar or othermedia format characteristics can be employed by those skilled in the artto use the invention with equal advantage to implement these techniques.Further, although embodiments have been described in the context of adisk drive with embedded servo wedges, the invention can be employed inmany different types of disk drives or other storage devices having ahead that scans the media.

What is claimed is:
 1. A method for optimizing a defect log for a mediumof a storage device, wherein the defect log comprises entries indicatingindividual locations in the medium of the storage and zone entriesindicating zones comprising a plurality of locations in the medium ofthe storage device, the method comprising: detecting defects inlocations in the medium of the storage device; recording the locationsof the defects into respective entries for individual locations in thedefect log; determining a quantity of defects that are adjacent ornon-adjacent within a first zone of locations based on the entries ofdetected defects; recording a zone entry in the defect log for the firstzone of locations when the quantity of defects within the first zoneexceed a threshold; and removing the respective entries of the defectsfrom the defect log that are within the zone entry for the first zone.2. The method of claim 1, wherein the zone entries indicating a zonecomprise a first parameter indicating a plurality of wedges and a secondparameter indicating a plurality of tracks.
 3. The method of claim 1,wherein recording the zone entry for the first zone of locations whenthe quantity of defects within the first zone exceed a thresholdcomprises recording the zone entry for the first zone of locations whenthe quantity of defects within the first zone exceed a threshold whenthe size of the defect log exceeds a threshold size.
 4. The method ofclaim 1, further comprising: determining when zones recorded in thedefect log are adjacent to one another based on their respective zoneentries; and combining the zone entries of adjacent zones into a singlezone entry encompassing the adjacent zones.
 5. The method of claim 4,further comprising determining that the size of the defect log exceed asecond threshold size prior to determining that the number of defectsdetected in adjacent zones and combining the zone entries of theadjacent zones.
 6. The method of claim 4, wherein the sizes of theadjacent zones are approximately equal.
 7. The method of claim 1,wherein the defect log is condensed prior to use of the storage devicewith a host device.
 8. The method of claim 7, further comprisingdetermining if a number of sectors identified in the defect log exceedsa threshold value.
 9. A disk drive comprising: a disk including aplurality of tracks of sectors having a plurality of wedges; a head toperform read operations from the disk including reading defects on thedisk; and a processor for controlling operations in the disk drive tocondense a defect log for the disk, wherein the defect log comprisesentries indicating defects located in individual sectors in the disk andzone entries indicating zones comprising at least a plurality of tracksand wedges, the operations comprising: detecting defects in sectors inthe disk of the disk drive, recording the locations of the defects intorespective entries for individual sectors in the defect log, determininga quantity of defects that are adjacent or non-adjacent within a firstzone based on the entries of detected defects, recording a zone entry inthe defect log for the first zone when the quantity of defects withinthe first zone exceed a threshold, and removing the respective entriesof the defects from the defect log that are within the zone entry forthe first zone.
 10. The disk drive of claim 9, wherein the zone entrycomprises adjacent and non-adjacent defects detected on the disk thatare in proximity to one another along a first axis corresponding to acircumferential direction for the plurality of wedges and a second axiscorresponding to a radial direction for the plurality of tracks.
 11. Thedisk drive of claim 9, wherein the processor performs operations furthercomprising determining that the number of log entries exceed a secondthreshold prior to recording a zone entry in the defect log for thefirst zone when the quantity of defects within the first zone exceed athreshold, and removing the respective entries of the defects from thedefect log that are within the zone entry for the first zone.
 12. Thedisk drive of claim 9, wherein the processor performs operations furthercomprising: determining that the number of defects detected in a secondzone exceed the first threshold; recording a second zone entry for thesecond zone; determining that the first and second zones are adjacent toone another based on the zone entry and second zone entry; and combiningthe zone entry and second zone entry into a single zone entry thatencompasses at least the first and second zones.
 13. The disk drive ofclaim 12, wherein the processor performs operations further comprisingdetermining that the number of log entries exceed a second thresholdprior to determining that the first and second zones are adjacent to oneanother based on the zone entry and second zone entry and combining thezone entry and second zone entry into a single zone entry thatencompasses at least the first and second zones.
 14. The disk drive ofclaim 12, wherein the sizes of the first and second zones areapproximately equal size.
 15. The disk drive of claim 9, wherein thedefect log is condensed prior to use of the disk drive with a hostdevice.
 16. The disk drive of claim 15, wherein the processor performsoperations further comprising determining if a number of sectorsidentified in the defect log exceed a threshold value.